stack/packages/harness/src/bundle.mjs

// The launch bundle: everything a managed session runs from, generated
// from one resolved role instance and written once into the run
// directory. prompt.md, policy.json, tools.json and manifest.json for both
// harnesses; settings.json (the gate hook) and mcp.json (the typed tools)
// for Claude Code. The Pi extension and the Claude gate stay at their
// source paths; the manifest records their digests.
//
// Each harness layer the bundle relies on is a row S0 line
// (docs/plans/2026-10-04_slice-1.md, "What S6 can rely on"); the manifest
// names them.

import { createHash } from "node:crypto";
import { mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { fileURLToPath } from "node:url";
import { typedTools, untypedActions } from "./tools.mjs";
import { claudeBuiltins, MCP_PREFIX } from "./gate.mjs";

export const BUNDLE_VERSION = 1;
export const HARNESSES = Object.freeze(["pi", "claude-code"]);
export const SOURCES = Object.freeze({
  piExtension: fileURLToPath(new URL("./pi-extension.mjs", import.meta.url)),
  claudeGate: fileURLToPath(new URL("./claude-gate.mjs", import.meta.url)),
  mcpServer: fileURLToPath(new URL("./mcp-server.mjs", import.meta.url)),
  gate: fileURLToPath(new URL("./gate.mjs", import.meta.url)),
  tools: fileURLToPath(new URL("./tools.mjs", import.meta.url)),
});
// S0 lines 1-5 for both harnesses; line 6 is the Agent SDK, which S6
// doesn't use.
const RELIES_ON = Object.freeze({
  pi: ["S0-1 tool_call block", "S0-2 a throw blocks", "S0-3 a missing -e refuses to start", "S0-4 external wall clock plus agent_end check", "S0-5 bash is limited by the tool limit only"],
  "claude-code": ["S0-1 command hook deny, no --bare", "S0-2 hook wrapped as <gate> || exit 2", "S0-3 a missing gate blocks through the wrapper", "S0-4 timeout -k 2 10 <gate> || exit 2 with hook timeout 20", "S0-5 bash is limited by the tool limit only"],
});
// The Claude hook: N = 10, K = 2, hook timeout 20, which leaves the
// margin the brief asks for above N + K.
const GATE_TIMEOUT = { n: 10, k: 2, hook: 20 };

export class BundleError extends Error {}

const sha256 = (text) => createHash("sha256").update(text).digest("hex");
const quote = (s) => {
  if (s.includes("'")) throw new BundleError(`path can't hold a single quote: ${s}`);
  return `'${s}'`;
};

// The harness, provider and model one instance runs with. The agent-layer
// `harness` and `model` variables win; otherwise the system's execution
// adapter and model. Anything outside the two harnesses refuses.
export function sessionModel(resolved) {
  const v = resolved.vars;
  const harness = v.harness ?? v["execution.adapter"];
  if (!HARNESSES.includes(harness)) throw new BundleError(`instance ${resolved.instance}: harness ${JSON.stringify(harness)} isn't one of ${HARNESSES.join(", ")}`);
  const model = v.model ?? v["execution.model"];
  if (typeof model !== "string" || !model) throw new BundleError(`instance ${resolved.instance}: no model`);
  return { harness, provider: v["execution.provider"] ?? null, model, thinking: v.thinking ?? null };
}

function prompt({ contract, resolved, session, tools, untyped }) {
  const lines = [
    contract.trimEnd(),
    "",
    "## This session",
    "",
    `- Business: ${resolved.business}. Role instance: ${resolved.instance} (definition ${resolved.definition}). Run: ${session.run}.`,
    `- Launched by: ${session.launchedBy}. Harness: ${session.harness}, model ${session.model}.`,
    `- Workspace: ${session.workspace}. File tools work inside it only.`,
    `- Built-in tools: ${resolved.limits.tools.length ? resolved.limits.tools.join(", ") : "none"}.`,
    `- Bus tools: ${tools.map((t) => t.name).join(", ")}. The broker decides every call; a refusal names its reason.`,
    "- Each message to you arrives as one turn. Your final answer goes back to the sender as the reply, so end each turn with the answer itself.",
    "- You never hold a token. You act on the tracker, the forge and other roles only through the bus tools.",
  ];
  if (untyped.length) lines.push(`- Actions you hold that have no bus tool yet: ${untyped.join(", ")}. Say so instead of working around it.`);
  return lines.join("\n") + "\n";
}

// buildBundle({ dir, resolved, contract, arbiter, tracker, credentials, session, piVersion, claudeVersion })
//   dir          the bundle directory, created here (0700)
//   resolved     resolveInstance(...) output
//   contract     the role contract's text
//   arbiter      true when the business names this instance as an arbiter
//   tracker      true when the broker has task verbs for the business
//   credentials  the broker's credentialStatus(...) for the instance (metadata only)
//   session      { run, launchedBy, workspace, toolSocket, turnMarker }
//   piVersion    the pinned pi version, for the manifest
//   claudeVersion  the host's `claude --version`, for the manifest
// Returns { manifest, files } with absolute paths.
export function buildBundle({ dir, resolved, contract, arbiter = false, tracker = false, credentials = [], session, piVersion = null, claudeVersion = null }) {
  const model = sessionModel(resolved);
  const tools = typedTools({ resolved, arbiter, tracker });
  const untyped = untypedActions(resolved, tools);
  mkdirSync(dir, { recursive: true, mode: 0o700 });
  const write = (name, text) => {
    writeFileSync(join(dir, name), text, { mode: 0o600, flag: "wx" });
    return [name, sha256(text)];
  };
  const policy = {
    harness: model.harness,
    workspace: session.workspace,
    tools: [...resolved.limits.tools],
    typed: tools.map((t) => t.name),
    network: resolved.limits.network,
    needs: Object.keys(resolved.credentials ?? {}),
    credentials,
  };
  const files = {
    prompt: join(dir, "prompt.md"),
    policy: join(dir, "policy.json"),
    tools: join(dir, "tools.json"),
    manifest: join(dir, "manifest.json"),
  };
  const digests = [
    write("prompt.md", prompt({ contract, resolved, session: { ...session, ...model }, tools, untyped })),
    write("policy.json", JSON.stringify(policy, null, 2) + "\n"),
    write("tools.json", JSON.stringify(tools, null, 2) + "\n"),
  ];
  const sources = { gate: SOURCES.gate, tools: SOURCES.tools };
  if (model.harness === "pi") {
    sources.piExtension = SOURCES.piExtension;
  } else {
    sources.claudeGate = SOURCES.claudeGate;
    sources.mcpServer = SOURCES.mcpServer;
    files.settings = join(dir, "settings.json");
    files.mcp = join(dir, "mcp.json");
    const node = process.execPath;
    const command = `timeout -k ${GATE_TIMEOUT.k} ${GATE_TIMEOUT.n} ${quote(node)} ${quote(SOURCES.claudeGate)} ${quote(files.policy)} || exit 2`;
    digests.push(write("settings.json", JSON.stringify({
      hooks: { PreToolUse: [{ matcher: "*", hooks: [{ type: "command", command, timeout: GATE_TIMEOUT.hook }] }] },
    }, null, 2) + "\n"));
    digests.push(write("mcp.json", JSON.stringify({
      mcpServers: { mosaic: { type: "stdio", command: node, args: [SOURCES.mcpServer, files.tools, session.toolSocket] } },
    }, null, 2) + "\n"));
  }
  const manifest = {
    bundleVersion: BUNDLE_VERSION,
    business: resolved.business,
    instance: resolved.instance,
    definition: resolved.definition,
    run: session.run,
    launchedBy: session.launchedBy,
    resolvedDigest: resolved.digest,
    ...model,
    piVersion: model.harness === "pi" ? piVersion : null,
    claudeVersion: model.harness === "claude-code" ? claudeVersion : null,
    builtins: model.harness === "pi" ? [...resolved.limits.tools] : claudeBuiltins(policy),
    typed: tools.map((t) => (model.harness === "pi" ? t.name : MCP_PREFIX + t.name)),
    untyped,
    skills: [],
    reliesOn: RELIES_ON[model.harness],
    gateTimeout: model.harness === "claude-code" ? GATE_TIMEOUT : null,
    files: Object.fromEntries(digests),
    sources: Object.fromEntries(Object.entries(sources).map(([k, p]) => [k, { path: p, sha256: sha256(readFileSync(p)) }])),
  };
  writeFileSync(files.manifest, JSON.stringify(manifest, null, 2) + "\n", { mode: 0o600, flag: "wx" });
  return { manifest, files, policy, tools };
}